Why not both?
Ranked playlists having arena based combat where weapons spawn in the same spot every time and everybody starts with the same gun/grenades/abilities
Social playlists having class based combat with dynamic weapon spawns
Welll there’s also no need to separate out the two into separate formats. Arena and loadout based gameplay are not mutually exclusive. This is because “arena” is a particular style of gameplay (not a spawning system, which incidentally predates the arena genre by a good margin) that simply tries to make the “best” possible single match-up between two or more players in an FPS format in more or less terms of maximizing the statistical validity of combat.
That is to say it’s fast paced, evenly balanced, and competitively driven, all qualities which in no way prohibit a loadout based system which can easily be made to contribute to those exact same qualities (with IMO better results than a traditional on-map spawning system).
I love the OP idea. Social playlists need to be more of an “arcade type” if you will, so the class based would work well. But it would suck to have that in ranked because literally ranks would be based on luck. In fact, I wouldn’t mind if the social gametypes were pretty much the same as H4 is now